[英]JComboBox customize vertical scrollbar
這個目的主要是美學,我已經在JTextArea上做了類似的事情,但是我無法弄明白或者可以從JComboBox上獲取彈出滾動條。 我通過將其設置為0來移除顯示在頂部的箭頭。
setUI(new BasicComboBoxUI(){
protected JButton createArrowButton(){
return new JButton(){
@Override public int getWidth() {
return 0;
}
@Override
public void setFocusable(boolean focusable) {
super.setFocusable(false);
}
};
}
});
這是一個JScrollPane里面的JTextArea,沒有箭頭和一個更細的條
getVerticalScrollBar().setPreferredSize(new Dimension(10, 0));
getVerticalScrollBar().setUI(new BasicScrollBarUI(){
@Override
protected JButton createDecreaseButton(int orientation) {
return createZeroButton();
}
@Override
protected JButton createIncreaseButton(int orientation) {
return createZeroButton();
}
private JButton createZeroButton() {
JButton jbutton = new JButton();
jbutton.setPreferredSize(new Dimension(0, 0));
jbutton.setMinimumSize(new Dimension(0, 0));
jbutton.setMaximumSize(new Dimension(0, 0));
return jbutton;
}
});
您可以覆蓋BasicComboBoxUI
的getPopup()
方法以創建新的BasicComboPopup
。 然后您可以訪問createScroller()
方法,通過覆蓋它,您可以返回自己的自定義JScrollPane
。
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.plaf.basic.BasicComboBoxUI;
import javax.swing.plaf.basic.BasicComboPopup;
import javax.swing.plaf.basic.BasicScrollBarUI;
import javax.swing.plaf.basic.ComboPopup;
public class Example {
public Example() {
JComboBox<Integer> comboBox = new JComboBox<Integer>();
for (int i = 1; i <= 10; i++) {
comboBox.addItem(i);
}
comboBox.setUI(new BasicComboBoxUI() {
@Override
protected ComboPopup createPopup() {
return new BasicComboPopup(comboBox) {
@Override
protected JScrollPane createScroller() {
JScrollPane scroller = new JScrollPane(list, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
scroller.getVerticalScrollBar().setUI(new BasicScrollBarUI() {
@Override
protected JButton createDecreaseButton(int orientation) {
return createZeroButton();
}
@Override
protected JButton createIncreaseButton(int orientation) {
return createZeroButton();
}
@Override
public Dimension getPreferredSize(JComponent c) {
return new Dimension(10, super.getPreferredSize(c).height);
}
private JButton createZeroButton() {
return new JButton() {
@Override
public Dimension getMinimumSize() {
return new Dimension(new Dimension(0, 0));
}
@Override
public Dimension getPreferredSize() {
return new Dimension(new Dimension(0, 0));
}
@Override
public Dimension getMaximumSize() {
return new Dimension(new Dimension(0, 0));
}
};
}
});
return scroller;
}
};
}
});
JPanel mainPanel = new JPanel();
mainPanel.add(comboBox);
JFrame frame = new JFrame("Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Example();
}
});
}
}
你可以試試下面的代碼從這個參考
private void updateScrollBar(JComboBox<E> box) {
Object comp = box.getUI().getAccessibleChild(box, 0);
if (comp instanceof JPopupMenu) {
JPopupMenu popup = (JPopupMenu) comp;
JScrollPane scrollPane = (JScrollPane) popup.getComponent(0);
jScrollPane.getVerticalScrollBar().setPreferredSize(new Dimension(35, 35));
}
}
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